The proposed research concerns a study of certain purified toxins from venom of the scorpion, Centruroides sculpturatus, Ewing. These studies include (1) the effects upon the neur-muscular junction of eachof these toxins in both cholinergic and adrenergic transmission; (2) the immunologocal properties of the isolated toxins and the ability of aatisera to one toxin to one toxin to cross-react with the others; (3) the effects upon the biological properties of chemical alteration of amino acid side chains in these toxins. BIBLIOGRAPHIC REFERENCES: Watt, D. D. andBabin, D.R. "Biological Properties ofToxins Isolatd from Scorpion Venom". Pharmacologist 17, No. 2, 246, 1975. (Abstract). This paper was presented at the Fall Meetings of the American Society for Pharmacology and Experimental Therapeutics. We are currently preparing a paper on these data for journal publication.